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      <title>线程池的核心属性有哪些？ - 交互式测验</title>
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    <body>
      <div class="main-wrapper">
          <div class="quiz-container">
            <div class="quiz-header">
              <h1>线程池的核心属性有哪些？ - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
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      <script>
        const quizData = [
  {
    "question": "在Java的`ThreadPoolExecutor`中，`corePoolSize`参数的核心作用是什么？",
    "options": [
      "定义线程池能够创建的最大线程数量，用于应对突发流量。",
      "定义线程池中始终保持活跃的线程数量，即使它们处于空闲状态。",
      "设定非核心线程在被回收前可以保持空闲的时间。",
      "指定用于存储等待执行任务的队列类型。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "`corePoolSize`是线程池的基本大小。线程池会维持这个数量的线程，即使它们是空闲的，也不会被回收（除非设置了`allowCoreThreadTimeOut`）。这确保了在有新任务到来时能够快速响应，而无需等待新线程的创建。",
    "source": "文档中「1. 核心线程数（corePoolSize）」部分",
    "hint": "思考一下，哪个参数决定了线程池的“常驻”线程数量？文档中的定义是：“线程池中始终保持的线程数量”。"
  },
  {
    "question": "根据文档描述，`ThreadPoolExecutor`的拒绝策略（handler）在什么情况下最可能被触发？",
    "options": [
      "当提交的任务为null时。",
      "当线程池中的核心线程数已满，但工作队列还有空间时。",
      "当线程池已达到`maximumPoolSize`且工作队列也已满时。",
      "当调用`executor.shutdown()`方法后，但队列中仍有任务时。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "拒绝策略是线程池的最后一道防线。当线程池的容量达到上限（即工作线程数达到`maximumPoolSize`）并且用于缓冲任务的工作队列（`workQueue`）也满了，此时线程池无法再接受新的任务，就会触发预设的拒绝策略。",
    "source": "文档中「7. 拒绝策略（handler）」部分",
    "hint": "拒绝策略是处理“无法接受新任务”的情况，想一想线程池在什么情况下会彻底饱和？"
  },
  {
    "question": "`keepAliveTime`参数在`ThreadPoolExecutor`中主要影响哪一类线程的生命周期？",
    "options": [
      "所有正在执行任务的线程。",
      "所有的核心线程（core threads）。",
      "超过`corePoolSize`数量的非核心线程（non-core threads）。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`keepAliveTime`定义了非核心线程（即线程数超过`corePoolSize`的部分）在空闲状态下可以存活的最长时间。当一个非核心线程空闲时间超过`keepAliveTime`，它就会被回收，从而在负载降低时帮助系统释放资源。",
    "source": "文档中「3. 空闲线程存活时间（keepAliveTime）」部分",
    "hint": "该参数用于在任务负载波动时动态调整线程数量，它主要针对的是哪部分“额外”的线程？"
  },
  {
    "question": "在`ThreadPoolExecutor`中，当一个新任务到来时，如果当前运行的线程数已达到`corePoolSize`且工作队列（workQueue）未满，线程池通常会采取什么行动？",
    "options": [
      "立即执行拒绝策略（handler）。",
      "将新任务放入工作队列中等待执行。",
      "创建新的线程来处理任务，直到达到`maximumPoolSize`。",
      "销毁一个核心线程以便为新任务腾出空间。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "这是`ThreadPoolExecutor`的标准工作流程：1. 如果运行线程数小于`corePoolSize`，则创建新线程处理任务。2. 如果运行线程数大于或等于`corePoolSize`，则尝试将任务放入工作队列。3. 如果工作队列已满，则尝试创建新线程（直到`maximumPoolSize`）。因此，在这种情况下，任务会被放入队列。",
    "source": "文档中「5. 工作队列（workQueue）」部分",
    "hint": "在核心线程都在忙的情况下，线程池的下一个缓冲层是什么？"
  },
  {
    "question": "在配置`ThreadPoolExecutor`时，如果希望对创建的线程进行自定义操作，例如设置特定的线程名称或优先级以便于调试和监控，应该使用哪个参数？",
    "options": [
      "handler",
      "workQueue",
      "threadFactory",
      "unit"
    ],
    "correctAnswerIndex": 2,
    "explanation": "`threadFactory`是一个用于创建新线程的工厂接口。通过提供自定义的`ThreadFactory`实现，我们可以完全控制新线程的创建过程，包括设置线程名称、是否为守护线程、线程优先级等，这对于线程管理和问题排查非常有帮助。",
    "source": "文档中「6. 线程工厂（threadFactory）」部分",
    "hint": "哪个参数的字面意思与“创建线程”直接相关？文档中提到它“用于创建新线程的工厂”。"
  },
  {
    "question": "当线程池的任务负载很高，导致工作队列已满，并且线程数已经达到了`corePoolSize`时，线程池会如何响应？",
    "options": [
      "开始创建新的非核心线程来处理任务，只要总线程数不超过`maximumPoolSize`。",
      "丢弃工作队列中等待时间最长的任务。",
      "直接拒绝所有新来的任务。",
      "等待核心线程变为空闲状态。"
    ],
    "correctAnswerIndex": 0,
    "explanation": "这是线程池扩展能力（弹性）的体现。当核心线程和工作队列都无法立即处理新任务时，线程池会尝试创建新的线程（非核心线程）来分担压力，这个过程的上限由`maximumPoolSize`参数控制。",
    "source": "文档中「2. 最大线程数（maximumPoolSize）」部分",
    "hint": "当核心资源用尽时，线程池会如何利用它的“最大容量”来应对压力？"
  },
  {
    "question": "文档中提到了线程池的多种状态，以下哪个状态代表线程池已调用`shutdown()`方法，不再接受新任务，但会继续处理工作队列中已存在的任务？",
    "options": [
      "TERMINATED",
      "SHUTDOWN",
      "STOP",
      "RUNNING"
    ],
    "correctAnswerIndex": 1,
    "explanation": "`SHUTDOWN`是线程池的优雅关闭状态。在这种状态下，线程池会拒绝所有新提交的任务，但会努力完成已经在工作队列中等待的任务，以及正在执行的任务。这是最常用的关闭线程池的方式。",
    "source": "文档中「8. 线程池的状态」部分",
    "hint": "这个状态是一种“平稳过渡”的关闭过程，它会“完成收尾工作但不再揽新活”。"
  }
];
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        let score = 0;
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            document.getElementById('quiz-footer').style.display = 'none';

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            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

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                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
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            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  